JP6198032B2 - HYDROGEN GENERATION CATALYST AND SYSTEM USING HYDROGEN GENERATION CATALYST - Google Patents

Description

The present invention relates to a hydrogen generation catalyst and a system using the hydrogen generation catalyst. More specifically, the present invention relates to a hydrogen generation catalyst that generates a reformed gas containing hydrogen (H ₂ ) from an exhaust gas containing moisture and heat discharged from various devices and a fuel. The present invention relates to a long-lived hydrogen generating catalyst and a system using the hydrogen generating catalyst with little deterioration in catalyst performance.

In recent years, reduction of carbon dioxide (CO ₂ ) emissions has been strongly desired in consideration of the global environment. In connection with this, development of the technique which reduces the discharge | emission amount of the carbon dioxide discharged | emitted from various devices, such as a combustor and an internal combustion engine, and the technique which improves the combustion efficiency in various devices is energetically performed. For internal combustion engines for automobiles, fuel efficiency has been steadily improved by improving combustion efficiency and reducing friction. However, as energy problems become more prominent, further reduction of carbon dioxide emissions and improvement of energy efficiency are required, and further effective technical development is required.

  At present, the heat discharged together with the exhaust gas is thrown away from the internal combustion engine. The ratio of exhaust heat to the energy balance of internal combustion engines is by no means small. If exhaust gas and exhaust heat energy can be recovered effectively, carbon dioxide can be directly reduced and a great fuel efficiency improvement effect can be obtained.

  It is known that energy can be recovered chemically by utilizing an endothermic fuel reforming reaction using exhaust gas containing moisture and heat. In this case, since the exhaust heat is recovered, not only the hydrogen-containing reformed gas having a larger calorie than the supplied fuel is obtained, but also the obtained hydrogen has an effect of promoting combustion in the internal combustion engine. It can also be expected to improve fuel efficiency. That is, since the above-described exhaust heat recovery effect is taken into consideration, carbon dioxide can be reduced extremely effectively.

  Conventionally, oxygen-containing carbonization is highly effective in steam reforming reaction of oxygen-containing hydrocarbons, and is less susceptible to coking even in an environment where oxygen gas is not present or in a low water / carbon molar ratio (S / C). For the purpose of providing a steam reforming catalyst for hydrogen and a steam reforming method for oxygen-containing hydrocarbons using the same, a carrier containing a composite oxide in which ceria and alumina are dispersed together in nm scale, A steam reforming catalyst is proposed that contains at least one metal element belonging to groups 8 to 10 of the long-period periodic table supported on a carrier and is a catalyst for reforming oxygen-containing hydrocarbons with steam. (See Patent Document 1).

JP 2010-207782 A

  However, in the study by the present inventors, there are various components in actual exhaust gas and fuel, and there is a problem that, for example, a sulfur component or the like causes a decrease in catalyst performance.

  The present invention has been made in view of such problems of the prior art. The object of the present invention is to provide a long-lived hydrogen generation catalyst with little deterioration in catalyst performance over a long period of time and a system for increasing the energy efficiency of various devices by utilizing hydrogen produced by the hydrogen generation catalyst. It is to provide.

The inventors of the present invention have made extensive studies to achieve the above object. And as a result, it contains aluminum oxide, a first catalyst component containing rhodium supported on aluminum oxide, and a second catalyst component containing phosphorus supported on aluminum oxide, and the rhodium content is 0.1 to 0.1. It was found that the above-mentioned object can be achieved by setting the content to 2 mass% and the phosphorus content to be 0.45 to 0.84 mass% , and the present invention has been completed.

That is, the hydrogen generation catalyst of the present invention is a hydrogen generation catalyst that generates a reformed gas containing hydrogen by reacting fuel and water vapor.
The hydrogen generation catalyst includes aluminum oxide, a first catalyst component containing rhodium supported on aluminum oxide, and a second catalyst component containing phosphorus supported on aluminum oxide, and the rhodium content is It is 0.1 to 2% by mass, and the phosphorus content is 0.45 to 0.84% by mass .

  Further, the system of the present invention is a system using a catalytic reactor including the hydrogen generation catalyst of the present invention, wherein at least a part of exhaust gas containing heat and moisture and fuel are used as the hydrogen generation catalyst. The reformed gas containing hydrogen is produced by reacting in the presence of.

The present invention includes aluminum oxide, a first catalyst component containing rhodium supported on aluminum oxide, and a second catalyst component containing phosphorus supported on aluminum oxide, and the rhodium content is 0.1. It was made into the structure which is -2 mass% and content of phosphorus is 0.45-0.84 mass% . Therefore, it is possible to provide a long-lived hydrogen generation catalyst with little deterioration in catalyst performance over a long period of time and a system for improving the energy efficiency of various devices by utilizing hydrogen generated by the hydrogen generation catalyst.

It is sectional drawing which shows the outline | summary of the catalyst for hydrogen production which concerns on one Embodiment of this invention. It is a lineblock diagram showing typically the system using the catalyst for hydrogen production concerning one embodiment of the present invention. It is a block diagram which shows a fuel reforming reaction measure typically. It is a graph which shows the time-dependent change of the hydrogen production ability of the catalyst for hydrogen production of each example.

  Hereinafter, the hydrogen generation catalyst of the present invention and the system using the hydrogen generation catalyst will be described in detail.

  First, a hydrogen generation catalyst according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an outline of a hydrogen generation catalyst according to an embodiment of the present invention. As shown in FIG. 1, the hydrogen generation catalyst 1 of the present embodiment includes aluminum oxide 3, a first catalyst component 5 containing rhodium supported on the aluminum oxide 3, and phosphorus supported on the aluminum oxide 3. A first hydrogen generation catalyst 1 ′ including the second catalyst component 7 is included. Further, the hydrogen generation catalyst 1 of the present embodiment includes an aluminum oxide 3, a first catalyst component 5 containing rhodium supported on the aluminum oxide 3, and a second catalyst component 7 containing phosphorus supported on the aluminum oxide 3. And a second catalyst for hydrogen production 1 ″ containing a third catalyst component 9 containing lanthanum.

  A reformed gas containing hydrogen can be generated by reacting fuel and water vapor with the hydrogen generation catalyst having such a configuration.

  Although not shown, in the present invention, only the first hydrogen generation catalyst may be included, or only the second hydrogen generation catalyst may be included.

  Here, as a 1st catalyst component, it is not limited to what contains rhodium, For example, what contains platinum, palladium, nickel, etc. can be mentioned. Rhodium, platinum, palladium, and nickel can be used alone or in combination of two or more. The rhodium, platinum, palladium and nickel in the first catalyst component are thought to be dispersed and supported on aluminum oxide in the form of oxides or metal simple substances or alloys having a particle size of several nanometers. Is unknown.

  And it is preferable to contain rhodium as a 1st catalyst component from a viewpoint that hydrogen can be produced | generated more selectively. The rhodium content is preferably low in terms of cost, but is preferably 0.1 to 2% by mass. When the rhodium content is increased, the catalyst performance improves as the rhodium content increases. In particular, a decrease in the catalyst performance is suppressed, but a performance improvement fee commensurate with the increase in the rhodium content is obtained. It becomes impossible. If the rhodium content exceeds 2% by mass, a side reaction is induced and coking becomes remarkable, which may rather cause a decrease in performance. Moreover, as an initial performance, even if the rhodium content is 0.1% by mass, it is sufficiently obtained. Considering further suppression of catalyst performance degradation, the rhodium content is more preferably in the range of 0.4 to 1.2% by mass.

  Nickel can also generate hydrogen relatively efficiently, but coking becomes prominent and tends to be inferior to rhodium in terms of catalyst performance degradation. However, the use of nickel is extremely advantageous in terms of cost. Furthermore, although platinum and palladium are inferior to rhodium in the ability to selectively generate hydrogen, there is an advantage that catalyst deterioration due to coking is less likely to occur. Therefore, it is preferable to produce a catalyst by an effective blending utilizing each characteristic.

  Further, the second catalyst component contains phosphorus, and it is typically considered that phosphorus is dispersed and supported on aluminum oxide in the form of an oxide, but details regarding the loading position and action are unknown. .

  Moreover, it is preferable that content of phosphorus is 0.1-1.3 mass%, for example, and it is more preferable that it is 0.4-1.0 mass%. If the phosphorus content is less than 0.1% by mass, the effect of addition may not be obtained. On the other hand, if the phosphorus content exceeds 1.3% by mass, the surface of the first catalyst component may be excessively coated, resulting in a decrease in catalyst performance. Phosphorus is one of typical catalyst poisoning components, and is generally considered to cause a decrease in catalyst activity. However, in the hydrogen generation catalyst of the present invention, when the content is within the above range, the deterioration of the catalyst performance can be reduced.

  Furthermore, the third catalyst component is not limited to those containing lanthanum, and examples thereof include those containing magnesium and barium. Magnesium, lanthanum, and barium can be used alone or in combination of two or more. In combination, not only mixing but also compounding can be performed. When such a 3rd catalyst component is contained, the fall of catalyst performance can be made less and a low-temperature activity can be improved further.

Further, the content of the third catalyst component including a component related to magnesium, lanthanum, barium, or any combination thereof is an oxide of magnesium oxide (MgO), lanthanum oxide (La ₂ O ₃ ), or barium oxide (BaO). It is preferably 6 to 25% by mass in terms of conversion, and more preferably 5 to 15% by mass. If it is in such a range, the catalyst performance can be further reduced, and the low-temperature activity can be further improved.

Furthermore, magnesium, lanthanum, and barium in the third catalyst component may be dispersed and supported on the surface of the aluminum oxide particles in the form of carbonates or oxides, and further exposed to a temperature of 800 ° C. or higher. In some cases, at least a part of the aluminate may be formed by reaction with the surface of the aluminum oxide. Covering the surface of the aluminum oxide by the formation of the aluminate is particularly preferable for suppressing the deterioration of the catalyst performance. This is because the acid sites present on the surface of aluminum oxide act as active sites that cause side reactions and promote the decomposition of fuel and the generation of coke, which may cause catalyst degradation. Moreover, it is thought that the formed aluminate effectively attenuates the catalyst poisoning action of the sulfur component by coexisting with phosphorus contained in the second catalyst component, and suppresses the deterioration of the catalyst performance. Examples of the aluminate of each component include compounds having a spinel structure or a perovskite structure such as magnesium aluminate (MgAl ₂ O ₄ ), lanthanum aluminate (LaAlO ₃ ), and barium aluminate (BaAl ₂ O ₄ ). be able to.

In the case of forming the aluminate, the content of lanthanum required to coat the outer shell of the aluminum oxide particles with the aluminate phase, for example, lanthanum aluminate, is the surface area of the aluminum oxide particles as a starting material and This is largely determined by the thickness of the lanthanum aluminate phase that covers the surface of the aluminum oxide particles. When the particle diameter of aluminum oxide is small, the total surface area becomes large, so the lanthanum content needs to be increased. On the other hand, when the particle diameter of aluminum oxide is large, the total surface area becomes small, so that the aluminum oxide particles can be covered with lanthanum having a relatively small content. Here, when lanthanum is excessively added to the particle surface, the dispersibility of lanthanum on the surface is lowered, and a lump of lanthanum oxide (La ₂ O ₃ ) is generated, and the first catalyst such as rhodium. There is a risk of adversely affecting the loaded state of the components. The content of lanthanum is preferably 5 to 15% by mass as lanthanum oxide (La ₂ O ₃ ). It is considered that the aluminum oxide particle surface can be effectively coated with lanthanum aluminate within such a range.

  In producing the lanthanum aluminate phase / aluminum oxide particles as described above, it is effective to use an aluminum oxide powder having a primary particle diameter of 0.2 to 1 μm as a starting material for aluminum oxide. In the present invention, aluminum oxide powder having a relatively large particle size is used as a starting material for aluminum oxide. As a result, lanthanum aluminate phase can be formed by effectively arranging the lanthanum component added later on the particle surface without forming extra pores, which is effective for activation of water and carbon dioxide. It is thought that a rough surface can be exposed.

  As the aluminum oxide, various alumina raw materials such as boehmite, γ-, θ-, and δ- can be used. However, the alumina raw material has a different surface state depending on the type, that is, the reactivity of the lanthanum component and the aluminum oxide surface changes, so in the formation of the lanthanum aluminate phase, the addition condition of the lanthanum raw material, the firing temperature condition, etc. Need to be adjusted. For example, when boehmite alumina is used, boehmite alumina has many hydroxyl groups on the surface and many pores. Therefore, it is also effective to crush the pores to some extent by preliminary firing. In this case, since the surface reactivity is relatively high, the lanthanum aluminate formation temperature can be relatively low. On the other hand, when θ-alumina is used as the starting material, since the pores are few and the reactivity of the particle surface is relatively low, the alumina surface is activated using a lanthanum-containing aqueous solution having a relatively low pH, and the firing temperature is further increased. Need to be promoted to promote the formation of lanthanum aluminate.

  When the aluminate is positively formed on the catalyst, the aluminum oxide particles as described above are immersed in an aqueous solution of lanthanum nitrate, carbonate, acetate, etc., dried, and calcined at about 700 to 800 ° C. A lanthanum aluminate phase is formed by reacting the lanthanum component dispersed on the surface of the aluminum oxide particles with the aluminum oxide on the surface of the particles. Depending on the pH condition of the aqueous lanthanum salt solution used, the dissolution state of the aluminum oxide particle surface changes, which affects the formation of the lanthanum aluminate phase. Furthermore, when additionally supporting an oxide of magnesium or barium, similarly, lanthanum aluminate phase / aluminum oxide particles are immersed in a mixed aqueous solution of magnesium, barium nitrate, carbonate, acetate, etc., dried and fired. Through the process, oxides of magnesium and barium are dispersed and supported on the particle surface. In this case, after immersing the lanthanum aluminate phase / aluminum oxide particles, a basic precipitation agent such as ammonia, urea, or ammonium bicarbonate is added to form a precipitate, a coprecipitation method, a uniform precipitation method, or a metal alkoxide. It is also possible to use a sol-gel method as a starting material.

  The form of the hydrogen generation catalyst of the present invention is not particularly limited, but the slurry containing the hydrogen generation catalyst powder was applied to a ceramic or metal honeycomb or foam monolith support. Those are preferred. A so-called offset honeycomb in which offset fins are provided inside the cells of the honeycomb-shaped monolithic carrier is extremely effective in increasing the effective utilization rate of the hydrogen generation catalyst. The number of cells or the number of pores of such a monolith carrier is preferably about 400 to 900 cells per square inch.

  The amount of the hydrogen generation catalyst applied to the monolith carrier is preferably about 50 to 200 g / L, although it varies depending on the material of the monolith carrier. In the case of a metal monolith support having no pores, catalyst particles can be effectively used even with a relatively small amount of catalyst for hydrogen generation, but the adhesion force of the hydrogen generation catalyst particles to the surface of the monolith support is a problem. It becomes. On the other hand, in a ceramic monolith carrier such as cordierite having pores, a relatively large amount of catalyst for hydrogen generation is required because hydrogen generation catalyst particles enter and embed the pores on the surface of the monolith carrier, The adhesion force of the hydrogen generation catalyst particles to the surface of the monolith support becomes relatively strong. However, if the coating amount of the hydrogen generating catalyst is too large, fuel molecules are difficult to reach the inner hydrogen generating catalyst particles, resulting in waste. In particular, if the coating amount exceeds 200 g / L, the proportion of the catalyst layer in which the reactive fuel molecules cannot reach cannot be ignored, and the pressure loss increases, which is not preferable.

  Next, a system using a hydrogen generation catalyst according to an embodiment of the present invention will be described in detail. The system using the hydrogen generation catalyst of the present embodiment is a system using a catalytic reactor including the hydrogen generation catalyst according to the embodiment of the present invention, and is at least a part of exhaust gas including heat and moisture. And a fuel are reacted in the presence of a hydrogen generation catalyst to generate a reformed gas containing hydrogen. In addition, about the catalyst for hydrogen production in this embodiment, since it overlaps with the said description, description is abbreviate | omitted.

  As described above, by applying the hydrogen generation catalyst according to the embodiment of the present invention described above, it is possible to utilize hydrogen generated by a long-life hydrogen generation catalyst with little deterioration in catalyst performance over a long period of time. . And since the catalyst for hydrogen generation has a long life with little deterioration in catalyst performance over a long period of time, the combustion in the internal combustion engine can be stabilized, the energy efficiency can be improved, and the fuel consumption can be greatly improved. .

  Further, in the system using the hydrogen generation catalyst of the present embodiment, the exhaust gas supplied to the hydrogen generation catalyst from an internal combustion engine, a combustor, a fuel cell, or any combination thereof mounted on an automobile. It is preferable to generate a reformed gas containing hydrogen and supply the generated reformed gas to the device. In addition, as one of the usage modes of the catalyst for generating hydrogen, as described above, exhaust gas containing moisture and heat was used on the vehicle with the aim of greatly improving the fuel efficiency of the automobile equipped with the internal combustion engine. A system that performs a hydrogen generation reaction to generate a reformed gas containing hydrogen and supplies the reformed gas to an internal combustion engine can be given.

  Furthermore, in the system using the hydrogen generation catalyst of the present embodiment, it is preferable that the device includes an exhaust circulation device, and the exhaust circulation device includes a catalyst reactor. Thereby, the energy efficiency of the device can be greatly improved.

  Further, in the system using the hydrogen generation catalyst of the present embodiment, it is preferable that an intake air variable device is provided on the upstream side of the catalyst reactor. By providing the intake air variable device, secondary air can be introduced and the amount thereof can be controlled with high response, so that it is possible to respond to rapidly changing exhaust conditions with high response. In order to improve the responsiveness to such exhaust conditions with large fluctuations, it is necessary to always expose the catalyst for hydrogen generation to appropriate conditions, and the amount of fuel supplied to the catalytic reactor is determined by the amount of exhaust, the amount of moisture, It is preferable to control according to the amount of oxygen. In order to effectively use the reformed gas containing hydrogen obtained by a system using a hydrogen generating catalyst mounted on an automobile, as described above, a catalytic reactor including a hydrogen generating catalyst is used. A system using a hydrogen generation catalyst that is provided in the exhaust gas circulation device and is supplied to the intake air of the internal combustion engine through the exhaust gas circulation device may be mentioned. Since such a system can simultaneously realize exhaust heat recovery and combustion efficiency improvement, high energy efficiency can be obtained. Hereinafter, the usage aspect of the practical hydrogen production catalyst under the practical operating conditions will be described in detail.

  Further, in the system using the hydrogen generation catalyst of the present embodiment, controlling the oxygen concentration in the inlet gas of the hydrogen generation catalyst to 0.4 to 1.8% by volume promotes the reaction from a low temperature. It is preferable from the viewpoint that it becomes possible, and particularly when the amount is 1.2% by volume or less, hydrogen is reacted by reacting at least a part of the exhaust gas containing heat and moisture with the fuel in the presence of the hydrogen generation catalyst. Preferably, the reformed gas containing is generated. When oxygen is supplied from oxygen-free conditions, the concentration of hydrogen obtained increases with an increase in the amount of oxygen supplied. However, when the oxygen concentration exceeds 1.2% by volume, the generated hydrogen is preferentially oxidized. This is disadvantageous for the generation of reformed gas containing hydrogen.

Further, in the system using the hydrogen generation catalyst of the present embodiment, the exhaust gas and the exhaust gas are adjusted so that the oxygen (O ₂ ) / carbon (C) molar ratio in the hydrogen generation catalyst is 0.1 to 0.27. It is preferable to control the ratio of fuel and air from the intake air variable device. It is more reasonable to control the amount of oxygen supplied to the catalytic reactor including the hydrogen generation catalyst in relation to the amount of fuel supplied. When the oxygen (O ₂ ) / carbon (C1 in fuel) molar ratio is within the above range, the effect of introducing oxygen can be effectively exhibited. A more preferable range is 0.15 to 0.20.

  As described above, by slightly supplying oxygen, the generation of reformed gas containing hydrogen can be promoted, so A / F is controlled and oxygen is increased within a range that does not adversely affect the performance of the hydrogen generating catalyst. It is effective to make it. In particular, under conditions where the exhaust temperature is low and the hydrogen generation reaction is disadvantageous in terms of speed, the amount of hydrogen required can be increased by supplying oxygen beyond the above range, but combustion increases due to increased hydrogen. It is important to control the amount of oxygen supplied in balance with the effect. As a method for supplying a slight amount of oxygen, for example, there is an exhaust circulation device that operates based on the predictive control disclosed in Japanese Patent No. 3918402, and a method that operates an intake air variable device provided in the device. It is not limited to.

  In the system using the hydrogen generation catalyst of the present embodiment, the device is an internal combustion engine, and the ratio of the air mass to the fuel mass (A / F) in the operating condition of the internal combustion engine is a rich atmosphere or a stoichiometric atmosphere. Sometimes, it is preferable to generate a reformed gas containing hydrogen by reacting at least part of the exhaust gas containing heat and moisture with the fuel in the presence of the hydrogen generating catalyst. This is because the reaction in the hydrogen generation catalyst is basically a steam reforming reaction, and carbon dioxide reforming can occur under high temperature conditions of 550 ° C. or higher, but once under the lean conditions where there is a lot of oxygen, hydrogen This is because even if is formed, it is immediately oxidized by oxygen.

Furthermore, in the system using the hydrogen generation catalyst of the present embodiment, moisture contained in the exhaust gas is an important reactant component other than oxygen. By controlling the exhaust gas and fuel to the catalyst for hydrogen generation, hydrogen is generated by controlling the water (H ₂ O) / carbon (C) molar ratio to exceed 1.5 based on the C1 of the fuel. Can be promoted. Since moisture is a reaction product of the fuel component, when the amount of moisture is small, the decomposition reaction of the fuel becomes dominant, the generation of reformed gas containing hydrogen becomes insufficient, and carbon deposition also becomes remarkable. As a result, the hydrogen generation catalyst is likely to deteriorate. On the other hand, if a large amount of exhaust gas is introduced to increase the water (H ₂ O) / carbon (C) molar ratio, it is disadvantageous in terms of space velocity. That is, since the contact time of moisture and fuel with the catalyst surface decreases, the reaction becomes insufficient. However, the water (H ₂ O) / carbon (C) molar ratio can be controlled to be higher under conditions where the fuel supply amount is controlled to facilitate coking and where the hydrogen generation effect is relatively small. Although there is a method of supplying moisture from other than exhaust gas, it requires a water tank and a water evaporator, which is disadvantageous in terms of overall energy efficiency.

On the other hand, the moisture content is governed by the required exhaust gas circulation rate in the mode. The amount of hydrogen required is determined from the exhaust gas circulation amount, and the supply amount of reformed gas containing hydrogen is determined accordingly. The amount of moisture that can be secured at this time is determined from the operating conditions. If the operating condition of the internal combustion engine is stoichiometric, it is considered that the amount of water necessary for promoting the steam reforming reaction is almost ensured. By controlling the amount of exhaust gas and the amount of fuel to the catalyst for hydrogen generation, the water (H ₂ O) / carbon (C) molar ratio exceeds 1.5 and 4.3 with respect to C1 of the fuel. Hydrogen generation can be promoted by controlling to be as follows. By ensuring the amount of water more than the equivalent amount, it is possible to reliably obtain the effect of improving the fuel consumption. Furthermore, by making it possible to introduce the secondary air and controlling the amount thereof with high response, it is possible to cope with exhaust conditions that fluctuate rapidly with high response.

  Next, a system using a catalytic reactor including the hydrogen generation catalyst of this embodiment will be described in detail with reference to the drawings. FIG. 2 is a configuration diagram schematically showing an example of a system using a catalytic reactor including a hydrogen generation catalyst according to an embodiment of the present invention.

  As shown in FIG. 2, the system 10 using the hydrogen generation catalyst of this embodiment is an example applied to an internal combustion engine 20 which is one of the devices. The internal combustion engine 20 includes an air flow meter 21, a hydrogen sensor 22, and a fuel injection device 23 in the intake system A, and an oxygen sensor 24, a back pressure control valve 25, and an exhaust gas purification catalyst 26 in the exhaust system B. The internal combustion engine 20 also includes an exhaust circulation device 30 that connects the exhaust system B to the intake system A. The exhaust gas circulator 30 includes a gas temperature sensor 31, a fuel injection device 32, an intake air variable device 33, a fuel evaporator 34, a catalytic reactor 35 including a hydrogen generation monolith catalyst 35a, a cooling device 36, a valve 37, and a flow meter 38. And a filter 39. In the exhaust system B, by controlling the back pressure control valve 25, at least a part of the exhaust gas containing heat and moisture together with the fuel supplied from the fuel injection device 32 is a catalytic reaction provided in the exhaust circulation device 30. A reformed gas containing hydrogen is generated by being supplied to and reacting with the monolith catalyst for hydrogen generation 35a included in the vessel 35. At this time, in order to facilitate the reaction in the monolith catalyst 35a for hydrogen generation, the oxygen sensor 24, the gas temperature sensor 31, and the catalyst temperature sensor 35b provided in the catalyst reactor 35, the temperature of the supplied exhaust gas and oxygen The amount of fuel supplied from the fuel injection device 32, the amount of oxygen supplied from the intake air variable device 33, and the temperature of the fuel evaporator 34 are adjusted by detecting the concentration and the temperature of the hydrogen generation catalyst 35a. In addition, the reformed gas containing hydrogen generated in the catalyst reactor 35 is cooled by the cooling device 36 and supplied to the intake system A through the filter 39 by adjusting the valve 37. At this time, the exhaust gas atmosphere is predicted from the amount of fuel supplied from the air flow meter 21, the flow meter 38, the hydrogen sensor 22 and the fuel injection device 23, and the operating conditions of the internal combustion engine 20, and the subsequent hydrogen generation catalyst is used. The execution conditions for the generation of reformed gas in the existing system 10 are appropriately controlled.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

Example 1
Γ-alumina having a specific surface area of about 180 m ² / g was added to the diluted rhodium nitrate aqueous solution, and the aqueous rhodium nitrate solution was stirred while heating to gradually remove moisture. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Further, rhodium was supported on aluminum oxide by firing at 500 ° C. for 2 hours in the air using an electric furnace. A rhodium-supported aluminum oxide (2% by mass Rh / Al ₂ O ₃ ) powder having a rhodium content of 2% by mass was obtained.

The 2 mass% Rh / Al ₂ O ₃ powder is poured into water and dispersed sufficiently, and then, while stirring, phosphoric acid is gradually added, a predetermined amount of phosphoric acid is added, and then heated. The mixture was stirred and water was gradually removed. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Furthermore, it baked at 500 degreeC in air | atmosphere for 2 hours using the electric furnace, and the phosphorus was carry | supported on the rhodium carrying | support aluminum oxide. A catalyst for hydrogen generation of this example comprising a phosphorus / rhodium supported aluminum oxide catalyst (2 mass% Rh-0.84 mass% P / Al ₂ O ₃ ) having a phosphorus (P) content of 0.84 mass%. Obtained.

( Reference Example 2, Reference Example 3)
Except that the addition amount of phosphoric acid was changed, the same operation as in Example 1 was repeated, and the hydrogen generation catalyst in each example ( Reference Example 2: 2% by mass Rh-0.12% by mass P / Al ₂ O _3, reference example 3: 2 wt% Rh-1.26 wt% P / _Al 2 _{O 3)} was obtained.

Example 4
Γ-alumina having a specific surface area of about 180 m ² / g was added to an aqueous solution of lanthanum nitrate (La (NO ₃ ) ₃ ), and the lanthanum nitrate aqueous solution was stirred while heating to gradually remove moisture. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Furthermore, the lanthanum was supported on aluminum oxide by firing at 500 ° C. for 2 hours in the air using an electric furnace. A lanthanum-supported aluminum oxide (10% by mass La—Al ₂ O ₃ ) powder having a lanthanum content of 10% by mass as lanthanum oxide (La ₂ O ₃ ) was obtained.

The 10% by mass La—Al ₂ O ₃ powder was added to the diluted aqueous rhodium nitrate solution, and the aqueous rhodium nitrate solution was stirred while heating in the same manner as in Example 1 to gradually remove moisture. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Furthermore, it baked at 500 degreeC in air | atmosphere for 2 hours using the electric furnace, and carried rhodium on the lanthanum carrying | support aluminum oxide. Content of rhodium rhodium lanthanum supported aluminum oxide is 2 wt% (2% Rh / 10 mass% _La-Al 2 _{O 3)} to obtain a powder.

The 2% by mass Rh / 10% by mass La-Al ₂ O ₃ powder was put into water and sufficiently dispersed, and then phosphoric acid was gradually added while stirring, and a predetermined amount of phosphoric acid was added. Thereafter, the mixture was stirred while heating to gradually remove moisture. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Furthermore, it was baked at 500 ° C. for 2 hours in the atmosphere using an electric furnace, and phosphorus was supported on rhodium / lanthanum supported aluminum oxide. A book comprising a phosphorus-rhodium-lanthanum-supported aluminum oxide catalyst (2% by mass Rh-0.60% by mass P / 10% by mass La-Al ₂ O ₃ ) having a phosphorus (P) content of 0.60% by mass An example hydrogen production catalyst was obtained.

(Example 5)
Γ-alumina having a specific surface area of about 180 m ² / g was added to an aqueous solution of barium nitrate (Ba (NO ₃ ) ₂ ), and the aqueous barium nitrate solution was stirred while heating to gradually remove moisture. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Furthermore, it was baked at 500 ° C. for 2 hours in the air using an electric furnace, and barium was supported on aluminum oxide. The content of barium to obtain a barium-supported aluminum oxide (10 wt% _Ba-Al 2 _{O 3)} powder is 10% by mass of barium oxide (BaO).

The 10% by mass Ba—Al ₂ O ₃ powder was added to the diluted rhodium nitrate aqueous solution, and the aqueous rhodium nitrate solution was stirred while heating in the same manner as in Example 1 to gradually remove moisture. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Furthermore, it baked at 500 degreeC in air | atmosphere for 2 hours using the electric furnace, and carried rhodium on the barium carrying | support aluminum oxide. Content of rhodium rhodium barium-supported aluminum oxide is 2 wt% (2% Rh / 10 wt% _Ba-Al 2 _{O 3)} to obtain a powder.

The 2 mass% Rh / 10 mass% Ba—Al ₂ O ₃ powder was put into water and sufficiently dispersed, and then phosphoric acid was gradually added while stirring, and a predetermined amount of phosphoric acid was added. Thereafter, the mixture was stirred while heating to gradually remove moisture. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Further, it was baked at 500 ° C. for 2 hours in the air using an electric furnace, and phosphorus was supported on rhodium / barium supported aluminum oxide. This consisting of phosphorus phosphoric, rhodium, barium-supported alumina catalyst content of (P) is 0.45 weight% (2 wt% Rh-0.45 wt% P / 10 wt% _Ba-Al 2 _{O 3)} An example hydrogen production catalyst was obtained.

(Example 6)
Γ-Alumina having a specific surface area of about 180 m ² / g was added to an aqueous solution of magnesium nitrate (Mg (NO ₃ ) ₂ ), and the aqueous magnesium nitrate solution was stirred while heating to gradually remove moisture. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Furthermore, it baked at 500 degreeC in air | atmosphere for 2 hours using the electric furnace, and carry | supported magnesium on the aluminum oxide. A magnesium-supported aluminum oxide (10% by mass Mg—Al ₂ O ₃ ) powder having a magnesium content of 10% by mass as magnesium oxide (MgO) was obtained.

The 10% by mass Mg—Al ₂ O ₃ powder was added to the diluted rhodium nitrate aqueous solution, and the aqueous rhodium nitrate solution was stirred while heating in the same manner as in Example 1 to gradually remove moisture. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Further, rhodium was supported on magnesium-supported aluminum oxide by firing at 500 ° C. for 2 hours in the air using an electric furnace. A rhodium / magnesium-supported aluminum oxide (2% by mass Rh / 10% by mass Mg—Al ₂ O ₃ ) powder having a rhodium content of 2% by mass was obtained.

The 2 mass% Rh / 10 mass% Mg—Al ₂ O ₃ powder was poured into water and dispersed sufficiently, and then phosphoric acid was gradually added while stirring, and a predetermined amount of phosphoric acid was added. Thereafter, the mixture was stirred while heating to gradually remove moisture. Next, the obtained powder was dried at 120 ° C. for a whole day and night to remove excess moisture, and the lump portion was pulverized into a powder. Further, it was baked at 500 ° C. for 2 hours in the air using an electric furnace, and phosphorus was supported on rhodium / magnesium supported aluminum oxide. A book composed of a phosphorus / rhodium / magnesium supported aluminum oxide catalyst (2 mass% Rh-0.52 mass% P / 10 mass% Mg-Al ₂ O ₃ ) having a phosphorus (P) content of 0.52 mass% An example hydrogen production catalyst was obtained.

(Comparative Example 1)
The rhodium-supported aluminum oxide (2% by mass Rh / Al ₂ O ₃ ) powder obtained in Example 1 was used as the hydrogen generation catalyst of this example.

(Comparative Example 2)
The rhodium / lanthanum-supported aluminum oxide (2% by mass Rh / 10% by mass La—Al ₂ O ₃ ) powder obtained in Example 4 was used as the hydrogen generation catalyst of this example.

  Table 1 shows the specifications of the hydrogen generation catalyst in each of the above examples.

[Performance evaluation]
Using the fuel reforming reaction apparatus 50 shown in FIG. 3, an evaluation test of the hydrogen generation performance of the hydrogen generation catalyst 1 of each of the above examples was performed. The obtained results are shown in Table 1 and a part thereof is shown in FIG. The “hydrogen generation performance ratio” in Table 1 is the ratio of the catalyst outlet hydrogen concentration after 50 hours (after endurance) in the catalyst performance evaluation test to the initial catalyst outlet hydrogen concentration in the following catalyst performance evaluation test. Here, steam reforming reaction was performed using actual regular gasoline containing about 35 mass ppm of sulfur as the fuel supplied from the fuel pump 52.

In the evaluation test, the particle size of the hydrogen generation catalyst 1 in each example was adjusted to a size of 355 to 500 μm, and 100 mg was weighed and packed in a quartz reaction tube 51 (outer diameter: 6 mm, inner diameter: 4 mm). . Further, nitrogen (N ₂ ) as a carrier gas is supplied from the nitrogen tank 53 at a supply amount of 120 mL / min, and the supply amount of regular gasoline supplied from the fuel pump 52 is 0.030 mL / min, supplied from the water tank 54. The supply amount of water (H ₂ O) was 0.120 mL / min. Therefore, H ₂ O / C (molar ratio) = about 4.2. The liquid fuel supply rate (LHSV) is 20 / hr. In addition, it heated by the preheater 57 in order to make catalyst outlet temperature into reaction temperature and to make 650 degreeC into reaction temperature, and compared the fuel reforming performance of the catalyst 1 for hydrogen production. In comparison, the generated hydrogen concentration in the reformed gas was measured using gas chromatographs 59a and 59b equipped with a flame ionization detector or a thermal conductivity detector. The catalyst temperature can be measured by a catalyst temperature sensor 35b composed of an inserted thermocouple. In the figure, 55 is an oxygen tank, 56 is a carbon dioxide tank, and 58 is an electric furnace.

From Table 1 and FIG. 4, the hydrogen generation catalysts of Examples 1 and 4 to 6 belonging to the scope of the present invention are supported on aluminum oxide as compared with the hydrogen generation catalysts of Comparative Examples 1 and 2 outside the present invention. It was found that rhodium, which is one of the first catalyst components, was supported and further phosphorus was contained, so that the catalyst performance was reduced and the life was long. Moreover, when the results of Example 1 , Reference Example 2, and Reference Example 3 are compared with the results of Examples 4-6, magnesium, lanthanum, and barium are further added, and the content thereof is 6 to 6 in terms of each oxide. It turns out that the fall of catalyst performance is further suppressed by setting it as 25 mass%.

  As mentioned above, although this invention was demonstrated with some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention.

  That is, in the above embodiment, the internal combustion engine is exemplified as the device. However, the present invention is not limited to this, and the present invention can also be applied to devices such as a combustor and a fuel cell.

1, 1 ′, 1 ″ Hydrogen generation catalyst 3 Aluminum oxide 5 First catalyst component 7 Second catalyst component 9 Third catalyst component 10 System 20 Internal combustion engine 21 Air flow meter 22 Hydrogen sensor 23 Fuel injector 24 Oxygen sensor 25 Back pressure Control valve 26 Exhaust gas purification catalyst 30 Exhaust gas circulation device 31 Gas temperature sensor 32 Fuel injection device 33 Intake air variable device 34 Fuel evaporator 35 Catalytic reactor 35a Monolith catalyst 35b for hydrogen generation Catalyst temperature sensor 36 Cooling device 37 Valve 38 Flow meter 39 Filter A Intake system B Exhaust system 50 Fuel reforming reaction device 51 Quartz reaction tube 52 Fuel pump 53 Nitrogen tank 54 Water tank 55 Oxygen tank 56 Carbon dioxide tank 57 Preheater 58 Electric furnace 59a, 59b Gas chromatograph

Claims (10)

A hydrogen generation catalyst that generates reformed gas containing hydrogen by reacting fuel and water vapor,
Aluminum oxide,
A first catalyst component comprising rhodium supported on the aluminum oxide;
A second catalyst component containing phosphorus supported on the aluminum oxide,
The rhodium content is 0.1 to 2% by mass,
A catalyst for hydrogen generation, wherein the phosphorus content is 0.45 to 0.84 mass% . The catalyst for hydrogen generation according to claim 1 , further comprising a third catalyst component containing at least one selected from the group consisting of magnesium, lanthanum and barium supported on the aluminum oxide. The content of the third catalyst component containing at least one selected from the group consisting of magnesium, lanthanum and barium is oxide conversion by magnesium oxide (MgO), lanthanum oxide (La ₂ O ₃ ) and barium oxide (BaO). The catalyst for hydrogen generation according to claim 2 , wherein the content is 6 to 25% by mass. 4. The hydrogen generating product according to claim 2 , wherein at least a part of the third catalyst component including at least one selected from the group consisting of magnesium, lanthanum, and barium forms aluminate. 5. catalyst. A system using a catalytic reactor including the hydrogen generation catalyst according to any one of claims 1 to 4 ,
A system for generating a reformed gas containing hydrogen by reacting at least a part of exhaust gas containing heat and moisture with a fuel in the presence of the hydrogen generating catalyst. The exhaust gas is an exhaust gas supplied to the hydrogen generation catalyst from at least one device selected from the group consisting of an internal combustion engine, a combustor, and a fuel cell mounted on an automobile,
6. The system according to claim 5 , wherein the reformed gas is supplied from the hydrogen generation catalyst to the device. The device comprises an exhaust circulation device,
The system according to claim 6 , wherein the exhaust circulation device includes the catalytic reactor. 8. The system according to claim 7 , wherein the exhaust gas circulation device includes a variable intake air device upstream of the catalytic reactor. The system according to any one of claims 5 to 8, wherein a concentration of oxygen in an inlet gas of the hydrogen generation catalyst is controlled to 0.4 to 1.8% by volume. From the exhaust gas, the fuel, and the air from the intake air variable device so that the oxygen (O ₂ ) / carbon (C) molar ratio in the inlet gas of the hydrogen generation catalyst is 0.1 to 0.27. The system according to claim 8 , wherein a ratio of at least one selected from the group is controlled.

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